The field of the present invention is receivers for wireless mobile devices. More particularly, the invention relates to a receiver module for a multimode radio.
Wireless devices are in wide use today, and users have an expectation that their wireless devices will operate nearly everywhere. However, the world has many different wireless communication standards, so for increased coverage, it is often necessary for a wireless device to support two or more standards. Such a wireless device is often referred to as a multi-mode device, as it has multiple radios to support its various operational modes. For example, a wireless mobile handset may support both a GSM mode and a CDMA mode. Typically, the handset will prefer one of the modes, and when powering up, will first determine if the preferred mode is available. If the preferred mode is not available, or if the preferred mode is dropped during operation, then the device will deactivate the preferred radio, and attempt to operate on the less-preferred mode. In another example, the wireless device may support GPS position location. Generally, the wireless device will deactivate all other radios while receiving GPS data. Since the GPS signal is relatively weak as compared to other communication signals, other active radios could significantly interfere with the reception of the GPS signals. In yet another example, a wireless mobile device may support several data transmission standards, such as Bluetooth®, 802.11, or a 3G telecommunications standard such as CDMA-HDR or WCDMA. In a similar manner as discussed above, typically, the device will prefer one of the data modes, and when powering up, will first determine if the preferred mode is available. If the preferred mode is not available, or if the preferred mode is dropped, then the device will deactivate the preferred radio, and attempt to operate on the less-preferred mode.
Wireless communication systems transmit and receive modulated radio frequency (RF) signals, generally in accord with one or more telecommunications standard. These telecommunication standards, such as GSM, CDMA, WCDMA, CDMA2000, UTMS, PDC, PHS, and others, generally set out specific and precise modes of operation. In a similar manner, several data transmission standards, such as Bluetooth, 802.11, and 3G also operate according to specific and precise modes of operation. Typically, each mode operates in a different frequency band, has different filter and signal conditioning requirements, and has different demodulation requirements. These differences not only affect the RF analog receive chain, but require different processing in the baseband frequency. Accordingly, a typical multi-mode radio will have a separate receiver module for each supported mode.
Although users have expectations that devices will work nearly everywhere, and are demanding more features and greater reliability, the physical size of the wireless devices is shrinking. With space already limited, and users demanding high-end features such as video cameras and music players, the space available for radio devices is shrinking quite dramatically. Further, each radio chain, even if deactivated, typically consumes at least some power. So even when a multi-mode device is operating in one mode, each of the other available radios is likely to be drawing at least some power. And in a portable device, with its limited battery life, the conservation of power is critical. Accordingly, there is a desire to include more radio modes on a wireless device, but limited space and power limitations need to be considered.